Rotatable bolt for submachine guns



Feb., 2, 1954 H. A. ASBY, JR

ROTATABLE BOLT FOR ySUBIVICI-{INE GUNS 5 Sheets-Sheet l Filed Oct. 24, 1947 Feb. 2, 1954 H. A. AsBY, JR

ROTATABLE BOLT FOR SUBMACHINE GUNS 5 Sheets-Sheet 2 Filed OCb. 24, 1947 Feb. 2, 1954 H. A. AsBY, JR

ROTATABLE BOLT FOR SUBMACHINE- GUNS 5 Sheets-Sheet 5 Filed OCC. 24, 1947 lI-llil Feb. 2, 1954 H. A. ASBY, JR 2,667,837

ROTATABLE BOLT FOR SUBMACHINE GUNS Filed oct. 24, 1947 5 sheets-sheet 4 D z /g a D Feb. 2, 1954 H. A. ASBY, JR 2,667,817

ROTATABLE BOLT FOR SUBMACHINE GUNS Filed Oct. 24, 194'? 5 Sheets-Sheet 5 Patented Feb. 2, 1954 1 Claim.

(Grantedunder Title 35, U. S. Code (1952),

' s ec. 266)' This invention relates -to an autoniatic irearm of the lightsubm-achine gruntypeandmcre particularly toimprovements vrtherein.

Most automatic firearms k of the submachine gun type are somewhat cumbersome and heavy t handle'due largely tothe designof the Aweapon and particularly Where tlieblow-backprinciple is utilized in such reari-ns. It is well known that such principlerequires aninertia member of large mass to resist the recoil iorces. While such weapons generally are relativelyinexpensive to manufacture, the `comparatively great Weight thereof makes them exceedinglyavvkward to handle and reduces the useful loadthat the soldier may carry with `him thereby limiting the usefulness of such az rearni.

Accordingly tit issanjobi ect or. this invention to provide an automatic iearrn, ,of light Y,Weight which oanbe readily and easilyhan'dled.

..f111othe1..obiect oivtliis invention is. vto provide a firearm of the autonjlatic type wherein the breech elements are contained. Within a unitary housing.

Still ancthe11bj9tpf .this invention `isnto provide, .imprOi/-cdbalrel guiding... and 'e. .filn

fora rearmai'ngf a. .1. me' bagel- The speciiic naturepf theuinve i 'nanas Well as other objects and adi/anta eswtlereot 1'fill' clearly -illustrated rig. i. anaemia 'in @after-f s onrriortorelease @fille helnglel .recoil movement.

Fig. G is a cross sectional viewtaken along line 5- of Fig. 2.

' Fig. 7-is a detailfragmentaryview showing the colt -ha-ndlecamA and -bolt Ahandle slot in the sleeve. Fig. Seis a VAfragmentary vcross sectional v.view

taken aiongthe line 8-.4-8 civ-Fig. 1,

Fig; 9 is-an enlarged detailview.showingthe -inannerofsecuring the bolt handleto the` bolt. l Fig. 10 is a .detail-.top vieW;of..thecover utilized .to pelose the rejection port .one .the :sleeve:

1 Fig. 11v iS ardetail yiewfotthe'rnt-plugand latching means, forlocking such plug to the sleeve.

Fig. 12.*is afdetail viev'v'of tlilevbol't, bolt barn', recoiljspring and recoil 'plug shown in the'locke'd battery position. i"

Fig. 13 is asimilar vewbut snowing the bolt prior to rotation to vtlielockeolp'osition by'the cam. A Y v j l; Fig. 1 4. isa cross sectional view taken along the line l-MciFig/ i Fig. l5`iis anenlarged detail view in longitudinal section showing the barrel guide means and barrel returnispri'ng indu tedat'tli forvvardend ofI the' sleeve.

Fig. 16 isa detail view of lthe receiver showing the magazine well and ejection `portthereini Fig. 17 is a longitudinal sectionalview of Fig. 18 is a cross sectional view taken along the linev iti-lll of Fig. 1'?. i

Fig. 19 is a cross sectional view taken along the line iii-I9 of Fig. 17.' f I' Fig. 2G isn an enlarged longitudinal sectional view of the ring mechanism.

Fig. 21 is 'an enlarged top View of the secondary scar asseinbled to'tlierib'of tlie"trigger"`gn"ard f..- .ef-i.. i: .-.1 i'. Fig. 22 is a side elevational view of Fig. 21. Fgl' 23` is `a"fragrnentarylongitudinal 'crosss'ectional view 'of' 'tlieb'oltf u Fig; Ziris' a Alon'g'ituclinal cross-sectional view "are" sncably 'contained' jwituiri a tubular sleeve and such members recoil approximately %"o`r" an inch upon discharge'of a.y cartridgeA to effect Auillockingof the bolt from' the receiver. The residual gas pressure then' forces the boltto'th end of its recoil 'stroke whereupon' a'recoil sp'ringrecover isutilized 'to-'block vthe re"'contro1 mechanism .so that' the r'earrn'can'not"betlischarged "unless such cover'is opened? Y There is shown inliig.` 4 in assembled relation a itirearnfroftlie automatic type'u'ch 'firearm Vcomprises a tubular sleeve l containing the major elernents iof ythe lrearrzrnamely, 'a barreLE, a

.receiver and a .1901i 4., A. trggersuardzimiisine manner as will be described, such housing containing the iire control mechanism. A magazine well 6 is secured to the underside of sleeve I immediately ahead of trigger guard housing 5 and is adapted to receive a cartridge magazine 1.

.Sleeve 'I is a long tubular member and is provided to house the breech elements of the iirearm' as mentioned above. The forward end of sleeve I is of an enlarged diameter as shown at 3 in Figs. 2, 3, 4, and l5, for a reason to be presently described.

Receiver 3 (Figs. 16, 17, 18 and 19) is a cylindrical member and is provided with an axial bore 9 and the forward end thereof is counterbored and threads I are provided therein. A cartridge ejectionY port I I is provided on top Vof receiver 3 to permit the red cartridge cases to be ejected therethrough. An opening I2 is provided on the underside of receiver 3 in alignment with magazine well 6 in order that a cartridge may be fed from magazine 1 into the barrel chamber. A transverse notch I3 is provided in receiver 3 at the rear end of ejection port I I to admit a locking lug as will be later explained. Such notch is formed on a suitable helix and a locking surface I4 is thereby provided against which the bolt 4 is locked as will be later described. A longitudinally disposed spline I5 is provided on the inside of receiver 3 t-o permit movement of the extractor 4I.

Receiver 3 is secured to barrel 2 by threads I5 and such assembly is slidably contained within sleeve I for limited longitudinal reciprocal movement therein. That portion of barrel 2 which lies within the large diameter B of sleeve I (Fig. 15) is of reduced diameter as shown at I5 and a shoulder I1 is formed by such reduced diameter. The portion I5 of barrel 2 extends forwardly a short distance whereupon the barrel is still further reduced in diameter and a threaded portion I8 is provided thereon.

A cup-like gland I9 surrounds reduced diameter I 6 of barrel 2 and abuts the rear end of enlarged diameter 8 of sleeve I. A barrel guide 20 is screwed onto threaded portion I8. A barrel return spring 2| surrounds reduced diameter portion I5 of barrel 2 between cup-like gland I9 and the rear face of barrel guide 2li. Such spring is provided to bias barrel 2 forwardly as will be later described. Barrel guide 25 provides a front bearing for barrel 2 so that such barrel will be properly aligned within sleeve I and yet be slidably mounted therein. Suitable detent means such as a split ring spring 22 is provided to prevent rotation of barrel guide 20 when such guide is properly adjusted. A plug 23 is screwed into the forward open end of sleeve I and is provided to arrest the forward movement of barrel 2 within sleeve I. A spring biased latch 25 on plug 23 engages a plurality of notches 24 provided on the front end of sleeve I to secure plug 23 against rotation.

Latch 25 essentially comprises a rectangular member, and a plurality of serrations 21 corresponding to notches 24 are provided on one end thereof. Latch 25 is contained within a suitable slot on plug 23 so that serrations 21 on the end thereof thereof engage notches 24. Plug 23 is counterbored as shown at 28 in Figs. 1l and 15 and a semi-circular spring 29 is secured to the bottom of such counterbore by rivets 30. A tang 3| is provided on spring 29 which is secured to rectangular latch member 25 by rivets 32. 'I'hus latch 25 is held in engagement with notches 24 by spring 29. Such latch may be readily disengaged from such notches by sliding latch 25 forwardly away from notches 24. The outer surface of latch 25 is serrated to facilitate such movement.

Bolt 4 (Figs. 2, 12 and 13) is a cylindrical member provided with an enlarged diameter rear end portion 26. An axial hole 33 is provided in bolt 4 which is of suitable conguration to receive a firing pin 34. An enlarged head portion 35 is provided on ring pin 34 which is contained within a counterbored portion 36 of hole 33. A helical spring 31 surrounds ring pin 34 and such. spring abuts the head 35 of ring pin 34 and the bottom of counterbored portion 35, such spring being provided to bias ring pin 351 rearwardly so that thenpoint thereof VVcan not accidently strike the primer of a cartridge. pin 39 in bolt 4 engages a transverse notch 39 on the forward end of ring pin 34 to secure such firing pin to the bolt and to permit limited longitudinal movement thereof.

A longitudinal slot 40 is provided on the forward end of bolt 4 in which is placed an extractor 4I. Such extractor is pivoted therein by a transverse pin 42. A spring 43 placed under the rear end of extractor 4I biases the forward end of such extractor into engagement with the rim of a cartridge. A longitudinally disposed locking lug 44 is provided on bolt Li which engages locking surface I4 on receiver 3. A suitable ejector (not shown) is contained in the face of the bolt. The rear end portion 26 of bolt 4 is counterbored and a cam 43 is provided in such portion, being disposed as shown in Figs. l2 and 13. On the forward end of portion 25 (Fig. 9) a radially disposed threaded hole 41 is provided to receive a bolt handle 48 to be later described.

A bolt cam 49 (Figs. 2, 3, 4, 5 and 13) is slidably contained within sleeve I adjacent the rear end of bolt 4. Such cam is a cylindrical member having a forwardly projecting end 59 which is provided with a cam surface 5I. Such cam surface cooperates with cam 46 to rotate bolt 4 to a. locked position as will be later described. A longitudinal groove 13| (Fig. 5) is provided on the bottom of bolt cam 49 which is engaged by a rib I32 on trigger guard housing 5 to maintain such cam in one position. The cylindrical body portion of bolt cam 49 is counterbored and one end of a recoil spring 52 is inserted therein. The other end of spring 52 is retained within sleeve I by a recoil plug 53. Such plug is secured to the end of sleeve I by threads 54. Plug 53 is secured against rotation in a manner similar to that for securing the front plug 23. An integral axially disposed spring guide 55 is provided on plug 53 which supports spring 52 contained within sleeve I and also arrests the rearward movement of bolt cam 49. A plurality of discs 53, preferably of ber, are secured to the bottom of the counterbored end of bolt cam 49 to cushion the shock of the recoiling members at the end of the recoil stroke, as shown in Fig. 5.

To prevent receiver 3 and. likewise barrel 2 from rotating Within sleeve I, a longitudinal slot 51 (Fig. 17) is provided on the bottom of receiver 3 near the rear end thereof. Such slot is engaged by a vertically disposed pin 58 mounted in the forward end of trigger guard housing 5. Trigger guard housing 5 (Figs. 4 and 6) is of built-up construction and comprises a trigger guard 59, a pistol grip 69 and side plates 6I and 62. These elements are preferably brazed to form a unitary structure. At the rear end of A transv'e'erse'n acertar;

housing 5, there is provided a tang-like end 63. Such end rests within a recess 64 formed by a strap 55 welded to the underside o sleeve I. The forward end of housing is secured to a depending lug |39 by a transverse headed pin t6 as shown .in Figs. 5, 6, and 8. Lug |30 is preferably secured to the underside of sleeve I by welding and abuts the rear surface of magazine well 6. A suitable spring detent B1 is provided to secure pin Se against displacement. Trigger guard housing 5 is readily disassembled from sleeve I by removing pin 65 so that the front end of such housing con be dropped away from sleeve I whereupon tang 63 can be readily removed from recess 64.

A hammer 68 (Figs. 2, 3, 4 and 5) of substantially triangular construction is pivotally mounted within trigger guard housing 5 by a transverse pin 69. A spring biased plunger is arranged as shown in the appended drawings to bias hammer 68 forwardly to strike firing pin 35i. A secondary scar notch H is provided in the upper rear apex of such hammer. A forwardly projecting lug 82 on hammer 68 integrally formed with the lower apex of such hammer is arranged to be engaged by soar notch 8| when hammer ES is in the cocked position as will be later shown.

,A secondary scar 7.2 is Dvotally mounted on a transverse pin 13 somewhat to the rear of hammer 68. Secondary sear 12 is biased forwardly by a spring 14 so that such scar can engage secondary Sear notch H on hammer 68. An upwardly projecting lug 15 is provided on secondary sear 12 which projects through a slot 'le provided on the underside of sleeve I so that such lug lies in the path of the bolt cam i9 for a purpose to be later described. Slot lo is of sunicient length to permit hammer 6B to rotate upwardly into sleeve I to strike iiring pin 34.

A trigger 11 and a safety latch 18 are mounted on a transverse pin 19 in trigger guard 59. Trigger 11 is provided with an upwardly projecting lug 80. Such lug is provided with a transverse scar notch 8|. A spring d3v is provided in back of trigger 11 to bias such trigger forwardly so that scar notch 8| will engage hammer BS upon release of such trigger. A substantially horizontal lug 855 is provided on trigger 11 which strikes a portion Sd of trigger guard housing 5 to limit the forward pivotal movement of trigger 11.

Safety latch 18 is a substantially L-shaped member, the lower portion of such member however is arcuately formed as shown at 36 and rests within slot 92 in trigger guard 59 to permit limited pivotal movement of latch 18. A spring 81 is placed between the arcuately formed portion 36 of latch 1S and portion 85 of trigger guard housing 5. Such spring is provided to bias the upright portion of latch 18 forwardly into engagement with a stud 88 mounted on a cover 89 as will be later described. A forwardlyv facing lug 99 is provided on latch 1'8v which rests on a horizontal shelf 9| provided on trigger guard housing 5 to limit the forward movement of the upright portion of latch 18.

A vertically disposed recess 93 is provided on the underside of trigger guard housing 5 on the forward end thereof. A magazine latch 94 is pivotally mounted therein by a transverse pin d5. Such latch comprises a Vertical arm 91 and a horzontal arm 98. and spring 06 is provided in the rear of arm 91 to bias such latch forwardly.

. The end of arm 98 rests on top of a shelf 9| of portion 85 to secure the rear end of such latch thereon.

An integral projection 99 is provided on the lower forward face of latch 9.4. Such projection is arranged to engage a corresponding lug I0 provided on magazine 1 to secure such magazine within magazine well 6. Projection 99 is readily rotated out of the path of lug |00 by pivoting latch 94 about pin 95 against the bias of spring 96 in a clockwise direction. This permits magazine 1 to drop out of magazine well S. The insertion of a loaded magazine into magazine well E cams projection 99 of latch se out of the path thereof until such projection is in back of lug |00, whereupon spring 96 biases latch 9d in a counterclockwise direction so that projection 99 engages lug |00.

Cover S9 is of suitable arcuate shape to surround the ejection port Il of receiver 3 and the corresponding opening |0| in sleeve I. Such cover is pivotally secured to sleeve l by a hinge |02. A hinge pin |03 is provided to secure the cover to hinge I 02 and a torsion spring Ille surrounds pin |03, Spring |04 is mounted in such fashion on pin ID3 and secured to cover 89 so as to normally maintain such cover in the open position. An integral downwardly projecting tab |635 is provided near the rear edge of cover 89 and stud 88 is secured to such tab preferably by a collar |06. In the closed position of cover 89 (Fig. I6), stud 88 assumes a substantially horizontal position. The inwardly projecting end of stud 88 is conically shaped as shown at |01 and a transverse slot |03 is provided on stud 88 which is engaged by safety latch 18 as will be presently described. A notch [09 (Fig. 1) is provided in cover 8o to permit such cover to clear bolt handle d8 when cover 89 is closed. Such notch likewise prevents bolt handle 40 from being retracted thereby providing a further safety feature.

When cover 89 is closed against the bias of spring |04, the conically shaped end |01 of stud 88 contacts the upright arm of latch 18 thereby rotating such latch slightly in a counterclockwise direction until slot |08 in stud 88 is aligned with the upright member of latch 18. Spring S1 then biases the upright arm of latch 18 in a clockwise direction so that such arm will engage slot il. llChus cover 89 is secured in a closed position. When in the closed position. the conically shaped end |01 of stud 88 contacts the forward end of lug 80 of trigger 11. Thus trigger 11 can not be pulled rearwardly to disengage hammer 68 from scar notch 8| on trigger 11. Thus there. is provided a simple and positive method of securing `the fire control mechanism in a safe position.

Bolt handle i8 (Figs. 6, 1, and 9) is a short cylindrical member and is provided with an end iI of reduced diameter. .Such end is threaded and is screwed into threaded hole 41 in bolt 4. A cam surface III is provided on the portion of bolt handle 138 adjacent threaded lend IIB for a purpose to be presently described. A cylindrical recess I I2 is provided in the other end of bolt handle i3 and a longitudinal slot I3 is provided in the wall of bolt handle |10 which communicates with recess ||2 and extends substantially the full length of bolt handle 48. A latch IM is pivotally mounted within slot I|3 by a transverse pin H5. A split ring spring IIB is placed within an annular groove H1 provided on bolt handle d8. Such spring likewise passes over latch I I and is provided to bias the lower end of latch IM into a slot |8 in bolt 4 when such bolt handle is assembled to bolt 4. Spring IIS likewise biases the upper end of latchv H4 into cylindrical recess |.|2. To pivot the lower. end of latch ||4 out of slot ||8 in order to unscrew bolt handle 43 from bolt 4, a cartridge ||9 may be inserted into cylindrical recess H2 and forced downwardly therein against the sloped upper end of latch I I4 thereby forcing such latch outwardly through slot H3 and forcing the lower end of such latch out of slot IIS thereby unlocking bolt handle 48 so that such handle may be readily disassembled.

Cam surface on bolt handle 48 cooperates with a corresponding cam surface |28 on sleeve I which effects unlocking of locking lug 44 on bolt 4 from locking surface |4 of receiver 3 whereupon bolt handle 48 travels rearwardly along a longitudinal slot |2| provided in sleeve I.

A forearm |22, preferably of wood, is secured to the underside of sleeve (Fig. 3) by a vertically disposed screw |23 which is threaded into a boss |24 provided on the underside of sleeve Y.

A front sight |25 is secured to the muzzle end of barrel 2 by any conventional means. A rear sight |26 is secured to the top of sleeve I near the rear end thereof by screws |21. Such sight may be any conventional type of sight utilized tion as shown on the appended drawings wherein an upright member |28 is integrally formed at right angles to a suitable base, and a sighting aperture |28 is provided in the upright member.

Operation The firearm illustrated in the appended drawings is charged by inserting a loaded magazine 1 into magazine well 6. Magazine latch 94 enrearwardly. Manual retraction of bolt handle 48 moves the breech elements rearwardly a distance of approximately 3/8 of an inch whereupon 'barrel guide 20 strikes the forward end of gland During the course of this movement, cam surface III of bolt handle 48 travels along cam surface |28 provided on sleeve The cooperation of these two cam surfaces rotates bolt handle 48 in a clockwise direction as shown in Fig. 6, thereby eifecting unlocking of locking lug 44 from locking surface I4. Upon unlocking of bolt 4, barrel return spring 2| biases receiver 3 and barrel 2 forwardly to the normal forward position. Continued rearward movement of bolt 4 forces hammer 68 to be rotated in a counterclockwise direction whereupon such hammer is engaged by sear notch 8| of trigger 11. Driving spring 52 returns bolt 4 and bolt cam 49 to the battery position upon release of bolt handle 48. Cam surface 5i provided on bolt cam 49 engages cam 4E provided on the rear end of bolt 4, thereby rotating such bolt to the locked position by rotation of lug 44 into engagement with locking surface |4 provided on receiver 3.

The firearm is now charged and a cartridge is chambered in the barrel. Release of hammer 88 is effected when trigger 11 is pulled rearwardly,

, rotating lug 80 in a clockwise direction which disengagessear notch 8| from lug 82 of hammer 68.

.25 on small arms but is preferably of the construc- Spring biased plunger 10 then forces hammer 88 in aclockwise direction to strike firing pin 84A whereupon the cartridge is discharged. The recoil force resulting from the discharge of the cartridge forces barrel 2, receiver 3, and bolt 4 contained within receiver 3, to move rearwardly approximately` of an inch whereupon unlocking of bolt 4 is effected as above described.

Hammer 88 is again rotated in a counterclockwise direction, but as trigger 11 is still held rearwardly, sear notch 8| is held out of engagement with lug 82 on hammer 88. However, secondary sear 12 is biased outwardly by spring 14 whereby secondary sear notch 1| provided on hammer 68 is engaged by secondary sear 12. Hammer 68 is thus held momentarily in the cocked position until bolt 4 is returned to its locked battery position by spring 52. Immediately after locking of bolt 4, bolt cam 49 strikes the upwardly projecting lug 15 of secondary sear 12 thereby rotating such sear in a clockwise direction. Such rotation causes secondary sear 12 to slip out of engagement with sear notch 1| on hammer 68. Thus hammer E8 is free to be biased forwardly by plunger 18 to strike firing pin 34.

It is desired to point out that the fire control mechanism herein described is for full automatic operation only. Accordingly such rearm can only be fired in bursts of short duration or long continuousvbursts. Release of trigger 11 at any time during firing permits sear notch 8| to reengage lug 82 of hammer 68 to hold such hammer in the cocked position.

Disassembly The rearm herein described is readily broken down into major assemblies for ease in cleaning, or to permit repair of damaged or broken parts. Trigger guard housing 5 is readily removed by forcing pin 66 outwardly whereupon the front end of such trigger guard housing may be pulled downwardly. Tang 63 is then readily removed from recess 64. Barrel 2, receiver 3 with the bolt mounted therein, and the bolt cam may then be readily removed by removal of front plug 23. Removal of such plug was previously described. The components just mentioned, along with the barrel guide 28 and gland I9 with barrel return spring mounted therein, can be readily removed from the muzzle end of the sleeve I. Removal of recoil plug 53 and spring 52 permits free access to the interior of sleeve for cleaning and oiling.

From the foregoing description it is readily apparent that there is here provided a light, sturdily constructed rearm that is positive in operation and one that can be readily and cheaply fabricated. This firearm is provided with a positive fire control mechanism for automatic fire and has positive safety features whereby the trigger is securely blocked to prevent accidental discharge of the firearm. Further, this firearm is positively locked at the moment of discharge of a cartridge and remains so for an appreciable length of time to permit safe unlocking at a substantially reduced breech pressure.

It is to be understood that the form of my invention, herewith shown and described, is to be taken asa preferred example of the same, and that various changes in the shape, size and arrangement of parts may be resorted to, without departing from the spirit of my invention, or the scope of the subjoined claim.

In an automatic firearm, a xed outer sleeve having a longitudinal slot terminating at its forward end in an enlarged cam portion, a barrel slidably mounted in said sleeve for limited recoil movement, a receiver iixedly secured to said barrel for movement therewith in said sleeve, said receiver having an axial bore therethrough, a bolt reciprocably mounted in said axial bore, said receiver including a rearwardly-disposed, uninterrupted, circumferential portion having a first cross sectional area, a further portion having a reduced cross sectional area immediately adjacent the forward end of said uninterrupted circumferential portion and forming a locking stop shoulder, and a transitional, helical locking surface between said reduced cross sectional area and said first-mentioned cross sectional area, a locking lug projecting from the side of said bolt in cooperative relationship with said reduced bore area and said helical locking surface to look said bolt in battery position, an operating handle sesured to said bolt rearwardly of said locking lug and said uninterrupted circumferential portion and extending through said longitudinal slot in said sleeve, a cam surface on said operating handle cooperating with said enlarged cam portion in said slot of said sleeve during recoil of said receiver to rotate said bolt in one direction for 16 disengaging said locking lug from said helical locking surface in said receiver, and single cam means for rotating said bolt in the opposite direction at the conclusion of counterrecoil movement for completely re-engaging said locking lug with said helical cam surface to lock said bolt in battery position.

HARRY A. ASBY, J R.

References Cited in the le of this patent UNITED STATES PATENTS 

